The present invention relates to construction materials and more particularly to protective or decorative coverings for block-type articles made of crushed cinder, glass, concrete, wood or clay.
In the building industry, it has long been recognized that it is desirable to provide masonry building blocks with protective coatings both for the purposes of extending the useful life of these materials as well as to improve their appearance where such blocks are exposed to view.
Cinderblocks, cement blocks, asbestos-cement blocks or the like have gained widespread acceptance in the building industry because of their ready availability and relatively low cost. One factor contributing to the relatively low cost of these construction blocks is the cheapness of the materials from which they are constituted. As a result, with the particular case of cinderblocks, for example, the surfaces of the blocks have a very rough character thus rendering painting or cleaning of the blocks a very time consuming endeavor.
As a result of the materials used in the construction of the blocks, it became apparent to workers in this field at an early time that suitable coatings or coverings would have to be applied to at least one surface of the blocks both to improve their appearance and to render them impervious to moisture and decay causing chemicals where such blocks were used in the subterranean foundations of building structures.
One of the most common solutions of the foregoing problem has consisted in the application of a thermosetting resin to one or more surfaces of the block such as, for example, in the U.S. Pat. Nos. to Sergovic, 2,751,775 of June 26, 1956 and 3,194,724 of July 13, 1965 and McClinton, 3,030,234, of Apr. 17, 1962. The coverings disclosed in the foregoing references, while generally providing a suitable protective layer, have suffered from the disadvantage that they have required that the article being covered be heated to obtain the best results.
In general the prior art attempts to provide coverings to the surfaces of modular elements have been directed to attempts to impregnate one or more surfaces of the blocks with a thermosetting or thermoplastic material which, at the outset of the process is in a liquid state. Subsequently, for the thermosetting materials, the process is completed by curing the coating either by the application of heat or by simply allowing the block with the coating material to stand at room temperature for a suitable amount of time. The thermoplastic materials, of course, harden upon cooling.
While the foregoing practices of the prior art have provided suitable coatings, the obtaining of such coatings has generally been time consuming chiefly in view of the emphasis placed upon filling the interstices of the block surfaces with the coating material.
The present invention avoids the foregoing and other disadvantages of the prior art methods while providing an extremely efficient method of covering one or more surfaces of a masonry block having a slightly modified construction, which covering will provide a durable, protective and, if desired, a decorative face for the block surface. In addition, the method of the present invention can be carried out at a substantially reduced cost relative to the processes of the prior art which is a factor of prime importance in the contemporary building trades. Also, with the method of the present invention, a building contractor can effect covering of the building blocks at the construction site itself thus eliminating the need for precisely calculating the number of covered blocks in advance that would have to be ordered from a supplier.
In summary, in one embodiment, the method of the present invention consists in placing a block that is provided with a locking groove about its exterior surface in an open top receptacle. The floor of the receptacle is provided with spacing studs on which the bottom of the block rests so as to be separated a small distance from the floor. The walls of the receptacle which extend upwardly from its floor are spaced apart a distance such that when the block is placed in the receptacle a small space will be provided between the exterior surfaces of the block and the interior walls of the receptacle. For the sake of efficiency, the lower edge of the locking groove of the block should be positioned so as to extend parallel to and co-planar with the top edges of the walls of the receptacle. A thermoplastic sheet having sufficient surface area to completely cover the exposed surface of the block, the locking groove and overlap the edges of the walls of the receptacle is heated to a temperature sufficient to render it deformable. The thickness of the sheet should be such that when at room temperature the sheet is relatively stiff. However, it should be understood that it is only necessary that the sheet be thick enough so that when heated and deformed, the sheet will retain its deformed configuration. The heated sheet is then draped over the exposed surface of the block in the receptacle and the interior of the receptacle which is connected to a vacuum line is exhausted to remove the air from the interior of the receptacle. The application of the vacuum to the interior of the receptacle has the effect of pulling the pliable thermoplastic sheet material into intimate contact with the locking groove of the block. It will be apparent that the application of the vacuum must be effected relatively rapidly after the sheet is draped over the block and preferably immediately. Subsequently, upon cooling, the thermoplastic sheet material hardens and that portion of the sheet material that is engaged in the locking groove functions as an anchor for the material thus providing a secure attachment of the sheet material to the block.
In addition to the advantages flowing from the improved type of covering provided by the present invention, it will be apparent that the method of the present invention readily lends itself to mass production in a completely automated system having the characteristics of both a high production output at a very low cost per unit produced. Additional advantages will be set forth and will become apparent to those skilled in this art in the detailed description which follows and in this description reference will be had to the accompanying drawings in which: